The Little of Power BI Visualization Design – Part 2

Continuing our journey on applying Andy Kirks tips and tricks from his series “The Little of Visualization Design” we are now at part 2, Clever Axis Scaling. As last time I suggest you read his post first so we already have some common ground.

Why use clever axis scaling

Clever axis scaling is a tool in order to create some drama in your visualization. It can also help you highlight values and draw your consumers eye towards it. Things that stand out will get attention, our brain is simple in this regard, and in this case that is what we are after.

In the example the y-axis is set to 50, but the maximum value is 76. Now, my quick thought was “Great! this is easy, lets just set the y-axis to 50 so the helper line is 50”. This is easy to do, however the chart actually gets cut at 50. So it ends up looking the image below, which is not what we want at all. We are now hiding the most interesting data!

Max y-axis value set to 50 truncates your graph

So I tried setting it to 100. Now, that works okay, but the highest line on the y-axis is now not 50 so the dramatic effect of 76 shooting way above the last helper line on the y-axis disappears even though we still see the biggest increase on the chart to the left. So what is the solution? You need to try out what works best with your data. In this case it seems to work fine to choose 76, the maximum value in the chart. Now this will not always be the case because we can not control how many lines on the y-axis we get. If I make the chart higher you can see that the y-axis changes with numbers as well.

Trying out different max values on the Y-axisDifferent heights can remove some of the effect we are after

Use it carefully

This solution also has the drawback that you are hardcoding the minimum and maximum value. So if you suddenly have a value higher than 76 you will loose it! In the end it comes down to what you want to tell with your chart, if your chart is going to change values often and how dramatic you want it. If you have no idea how your numbers will behave in the future I will not advice you to hard code min/max values unless you need it for a specific occation like a presentation. When you are done with that spesific occasion I suggest you turn them back to automatic to minimize confusion.

Final result

As with all tools PowerBI has some limitations compared to custom code and for example using something like D3.js where you can do absolutely everything you want! Having these limitation can make it a challenge to use all these tips and tricks going forward, but we will do the best we can! In this case we might have some problems trying to create a more dramatic effect in our storytelling. Both with your axis’ as we have seen here, but also with data labeling as PowerBI does not let you choose which data points to highlight. So if you try to label the highest value without hovering over it it is not possible. Or at least I didn’t manage to, but if you do please let me know how you did it.

Also, if anyone has a way of hiding the ESRI logo in Power BI Desktop please let me know. They are not pretty and are driving me crazy!